Thetis-class patrol boat

Thetis-class patrol boats, also called the Argo-class patrol boats, were a class of 18 steel-hulled cutters of the United States Coast Guard built from 1931 to 1934.^[2][3][4]

USCGC Argo (WPC-100) underway during World War II, circa 1944.
Class overview
Name	Thetis class
Operators	United States Coast Guard
Built	1931–1934
In commission	1931–1967
Completed	18
Preserved	1
General characteristics
Type	Patrol boat[1]
Displacement	337 long tons (342 t) (1933) 350 long tons (360 t) (1945)
Length	165 ft (50 m)
Beam	25 ft 3 in (7.70 m)
Draft	7 ft 8 in (2.34 m) (1933) 10 ft 0 in (3.05 m) (1945)
Installed power	1,340 bhp
Propulsion	2 × Winton Model 158 6-cylinder diesels 1,340 bhp (1,000 kW)
Speed	11 kn (20 km/h; 13 mph) cruising 16 kn (30 km/h; 18 mph) maximum
Range	1,750 statute miles (14 knots) 3,000 statute miles (11 knots) 6,417 statute miles (6 knots)
Complement	44 (1933) 75 (1945)
Sensors & processing systems	None (1933 SF radar (1945) QCO sonar (1945)
Armament	1933 1 × 3-inch gun 1 × 1-pounder gun 1941 1 × 3-inch gun 1 × Y-gun 2 x depth charge tracks 1945 2 x single-mount 3-inch/50-caliber gun 2 x single mount 20 mm/80 cannon 2 x depth charge tracks 2 x Y-guns 2 x Mousetraps

Development

On 17 January 1920, the Volsted Act went into force in the United States. The law enforced the Eighteenth Amendment, which banned the "manufacture, sale, or transportation" of most alcohol and began the period of Prohibition.^[5][6]: 11 The Volsted Act, in turn, was enforced by police departments, the Bureau of Prohibition, the Customs Service, the Treasury Department, and the USCG.^[6]: 11 The USCG's role was to prevent seaborn alcohol smuggling, a role initially deemed small and manageable. By 1924, the service was overwhelmed by the volume of smugglers and struggled to intercept 5% of violators. Aside from normal duties, it shifted to impose a blockade along 5,000 miles (8,000 km) of American coastline. For the new role, new cutters, patrol boats, and ex-USN destroyers joined the fleet to patrol at sea as Prohibition enforcement became the first priority for the USCG.^{[6]: 161-164} While the ships helped fill gaps off the coast, they were expensive to operate and performed poorly. In the 1930s, the USCG began to build purpose-build patrol boats to take over enforcement.^{[7]: 382–383} These new ships varied in size and capability, and were used to create a continuous buffer of Prohibition enforcement that stretched from the open ocean to inner harbors.^{[8]: 89, 95, 99, 105}

A common tactic by smugglers was to use large, seagoing, "mother ships" that loitered off the coast and supplied alcohol to smaller boats that then brought the drinks ashore.^[8]: 108 The USCG built the 125 ft (38 m)-long Active class cutters to trail and intercept mother ships, and the experience was used to develop the next class of sea-going cutters.^[9]: 166 The resulting 165-foot "B"-class,^{[10][9]: 166} named for the cutters' overall length^[10] and also known as the Argo and Thetis-class, resulted.^[9]: 166 The design was intended to balance and exceed in speed, seaworthiness, range, radio equipment, and armament.^[11]: 100 Eighteen cutters were built, and they were large and fast enough to intercept the mother ships.^[8]: 108

Ships

• USCGC Argo (WPC-100)
• USCGC Ariadne (WPC-101)
• USCGC Atalanta (WPC-102)
• USCGC Aurora (WPC-103)
• USCGC Calypso (WPC-104)
• USCGC Cyane (WPC-105)
• USCGC Daphne (WPC-106)
• USCGC Dione (WPC-107)
• USCGC Electra (WPC-187)
• USCGC Galatea (WPC-108)
• USCGC Hermes (WPC-109)
• USCGC Icarus (WPC-110)
• USCGC Nemesis (WPC-111)
• USCGC Nike (WPC-112)
• USCGC Pandora (WPC-113)
• USCGC Perseus (WPC-114)
• USCGC Thetis (WPC-115)
• USCGC Triton (WPC-116)